Communications device

ABSTRACT

A communications device comprising a transmitter, a receiver and a controller operable to transmit and to receive signals representing data to and from a network element across a first wireless access interface, the first wireless access interface being provided by the network element and access to resources of the first wireless access interface being controlled by the network element. The controller is configured to control the receiver to perform detection of signals transmitted across a second wireless access interface, and to control the transmitter to transmit a reporting message to the network element across the first wireless access interface, the reporting message including an indication of one or more properties of signals that have been detected across the second wireless access interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase application based on PCTInternational Patent Application No. PCT/EP2014/076784, filed on Dec. 5,2014, and claims priority to European Patent Application No. 14151346.5,filed in the European Patent Office on Jan. 15, 2014, and the entirecontents of each of the above applications are incorporated herein byreference.

FIELD OF THE DISCLOSURE

The present disclosure relates to the wireless telecommunicationssystems and in particular communications devices, network elements,communications systems and methods for performing remote signaldetection.

BACKGROUND OF THE DISCLOSURE

Third as well as fourth generation mobile telecommunication systems,such as those based on the 3GPP defined UMTS and Long Term Evolution(LTE) architecture are able to support more sophisticated services thansimple voice and messaging services offered by previous generations ofmobile telecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as video streaming andvideo conferencing on mobile communications devices that wouldpreviously only have been available via a fixed line data connection.The demand to deploy fourth generation networks is therefore strong andthe coverage area of these networks, i.e. geographic locations whereaccess to the networks is possible, is expected to increase rapidly.However, although the coverage and capacity of fourth generationnetworks is expected significantly exceed those of previous generationsof communications networks, there are still limitations on both thenetwork capacity and the geographical areas than can be served by suchnetworks. These limitations may for example be particularly relevant insituations where networks are experiencing high load and high-data ratecommunications. Although the licensed frequency spectrum available tomobile communications system may increase and therefore allows forcapacity to be increased further, future growth in demand may lead toinsufficient licensed frequency spectrum being available to providesufficient capacity to meet demand. As a consequence of this limitedspectrum, the use of unlicensed portions of the frequency spectrum hasbeen proposed for LTE systems, where the additional frequency spectrummay be used to supplement the licensed spectrum available and thereforeincrease the capacity of LTE systems. However, in contrast to licensedportions of the frequency spectrum, unlicensed portions may be used by abroad range of systems which may both cause interference but also besusceptible to interference.

SUMMARY OF THE DISCLOSURE

In accordance with one example the present disclosure there is provideda communications device comprising a transmitter, a receiver and acontroller operable to transmit and to receive signals representing datato and from a network element across a first wireless access interfaceoperating according to a first wireless telecommunications standard, thefirst wireless access interface being provided by the network elementand access to resources of the first wireless access interface beingcontrolled by the network element. The controller is configured tocontrol the receiver to perform detection of signals transmitted acrossa second wireless access interface operating according to a secondwireless telecommunications standard which is different to the firstwireless telecommunications standard, and to control the transmitter totransmit a reporting message to the network element across the firstwireless access interface, the reporting message including an indicationof one or more properties of signals that have been detected across thesecond wireless access interface.

Detecting signals transmitted across a second wireless access interfaceat a communications device being served by a network element operatingaccording to a first telecommunications standard, and providing anindication of the results of the detection to the network element allowsthe network element to perform remote signal detection. This thereforeenables the network element to acquire knowledge of signals which it maynot be able to detect directly because it is out of range but which thecommunications device may be able to receive. This therefore allows thenetwork element to obtain improved information on signals providedacross other wireless access interfaces operating according to othertelecommunications standards that are operating within its coverage areacompared to sensing the signals directly. With this information on thesignals transmitted across a second wireless access interface, thenetwork element may then provide a third wireless access interfacepositioned around the signals transmitted across the second wirelessaccess interface so that the provision of the third wireless accessinterface does not interfere with communications across the secondwireless access interface. The provision of a third wireless accessinterface in this manner may include positioning the third wirelessaccess around the signals transmitted with respect to the secondwireless interface in both time and or frequency, thus enablingefficient use to be made of the available spectrum.

In another example the signals transmitted across the first wirelessaccess interface are transmitted across a first frequency range and thesignals transmitted across the second wireless access interface aretransmitted across a second frequency range, the first and secondfrequency ranges being substantially mutually exclusive.

The detection of signals over a frequency range different to that thatthe communications device and the network element are communicating overenables the network element to establish unoccupied frequencies in apreviously unknown frequency range. These unoccupied frequencies maythen be used to provide increased capacity via the provision a furtherwireless access interface in addition to the first wireless accessinterference without interfering with the signals transmitted across thesecond wireless access interface.

In another example the controller is configured to control the receiverto receive a sensing request message from the network element, thesensing request message providing an indication of the second frequencyrange, and to control the receiver to perform the detection of signalstransmitted across the second wireless access interface using the secondfrequency range in response to receiving the sensing request message.

The use of a sensing request messages allows the network entity toinitiate the signal detection when it may wish to establish a thirdwireless access interface in order to provide additional capacity forcommunications devices.

In another example the receiver is operable to perform the detection ofsignals transmitted across the second wireless access interface inaccordance with one or more of a plurality of detection techniques, eachof the plurality of detection techniques having a different level ofsensitivity to the signals transmitted across the second wireless accessinterface.

This feature allows the technique used for signal detection to beselected based on the capabilities of the communications deviceperforming the detection and the sensitivity of the signal detectionrequired. This may for example allow the complexity of communicationsdevices to be reduced and in some examples the power consumption to alsobe reduced when relatively low sensitivity signal detection is required.

In another example the controller is configured to control thetransmitter to transmit to the network element an indication of one ofmore of the plurality of detection techniques the receiver can perform.

In another example one of the detection techniques includes detection ofthe energy present in the second frequency range.

In another example wherein the signals transmitted across the secondwireless access interface represent one or more packets, each packetincluding a preamble portion, a header portion and a data portion, andone of the detection techniques includes detection of the preambleportion.

In another example the signals transmitted across the second wirelessaccess interface represent one or more packets, each packet including apreamble portion, a header portion and a data portion, and one of thedetection techniques includes detection of the preamble portion anddetection and estimation of the data of the header portion.

In another example wherein the signals transmitted across the secondwireless access interface represent one or more packets comprising data,each packet including a preamble portion, a header portion and a dataportion, and one of the detection techniques includes detection of thepreamble portion, detection and estimation of data of the headerportion, and detection and estimation of data of the data portion.

The provision of different signal detection techniques allows atechnique appropriate to the communications device's capabilities andthe information required by the network element to be selected. Forinstance, energy detection may be used at a relatively simplecommunications device whereas full detection and estimation of packetsmay be used at a fully capable communications device such as a smartphone. Furthermore, the use of different signal detection techniquesalso allows the provision of a third wireless access interface by thenetwork element to be performed with a higher degree of adaptability andtherefore efficiency. For example by obtaining the header informationthe duration of the packet may be known and the third wireless accessinterface may be provided around the packet thus increasing theefficiency of the use of the available spectrum.

In another example the data portion includes collision avoidanceinformation, and the controller is configured to perform virtual carriersensing of the second wireless access interface based upon the collisionavoidance information and provide an indication of the virtual carriersending in the reporting message.

In another example the second frequency range includes frequencies froman unlicensed portion of the radio frequency electromagnetic spectrum.

In another example the second wireless access interface operatesaccording to one or more of the IEEE 802.11 standards.

In another example the first wireless access interface operates inaccording to a 3GPP LTE standard.

In another example the properties of the detected signals includes oneor more of temporal properties and power spectral density properties.

Specifying that the second wireless access interface operates inaccordance with IEEE 802.11 ensures that the provision of a thirdwireless access interface by the network element over the secondfrequency range will result in little or no interference with IEEE802.11 systems. Furthermore, the use of an unlicensed spectrum toprovide an additional wireless access interface by a LTE operablenetwork element allows the capacity of LTE system to be increasedwithout increasing the requirement of licensed spectrum, thus reducingthe cost of providing extra capacity in LTE systems.

Various further aspects and embodiments of the disclosure are providedin the appended claims, including but not limited to network elements,wireless communications systems and methods of the performing remotesignal detection.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described by way ofexample only with reference to the accompanying drawing in which likeparts are provided with corresponding reference numerals and in which:

FIG. 1 provides a schematic diagram of a wireless communications system;

FIG. 2 provides a schematic diagram of a communications device and anetwork element of a wireless communications system;

FIG. 3 provides a schematic diagram of a first and a second wirelesscommunications systems with overlapping coverage areas;

FIGS. 4a to 4c provides a schematic diagram of example licensed andunlicensed portions of the electromagnetic spectrum;

FIG. 5 provides a schematic diagram of a message exchange between anetwork element and a communications device performing remote signaldetection;

FIG. 6 provides a schematic diagram of IEEE 802.11 packet;

FIG. 7 provides a schematic diagram of a message exchange in virtualcarrier sensing routine; and

FIG. 8 provides a schematic diagram of overlapping coverage areas oftransmitting, receiving communications device and a third partycommunications device.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Conventional Communications System

FIG. 1 provides a schematic diagram of a conventional mobilecommunications system 100, where the system includes mobilecommunications devices 101, infrastructure equipment 102 and a corenetwork 103. The infrastructure equipment may also be referred to as abase station, network element, enhanced node B (eNodeB) or acoordinating entity for example and provides a wireless access interfaceto the one or more communications devices within a coverage area orcell, and over which the one or more mobile communications devices maycommunicate data. The network element is communicatively linked to thecore network 103 where the core network is connected to one or moreother communications networks and may also provide functionalityincluding authentication, mobility management, charging and so on forthe communications devices served by the network entity. The mobilecommunications devices may also be referred to as communicationsterminals or user equipment (UE) and are configured to communicate withone or more other communications devices via the network entity bytransmitting and receiving data via the wireless access interface overthe two way communications links represented by lines 104 to 109, where104, 106 and 108 represent downlink communications from the networkentity to the communications devices and 105, 107 and 109 represent theuplink communications from the communications devices to the networkentity. The communications system 100 may operate in accordance with anyknown protocol, for instance in some examples the system 100 may operatein accordance with the 3GPP Long Term Evolution (LTE) telecommunicationsstandard and in which the network element and communications devices arecommonly referred to as eNodeB and UEs respectively.

FIG. 2 provides a schematic diagram of examples UEs 101 and an eNodeB102. The UE includes a transmitter 201, a receiver 202 and a controller203 where the controller is configured to control the receiver 202 todetect signals representing control data and user data transmitted bythe eNodeB 210, and to estimate the data conveyed by these signals. Insome examples the control may also be operable to control the receiver202 to detect to detect signals transmitted by other wirelesscommunications systems over other wireless access interfaces. Thecontroller 203 is also configured to control the transmitter 201 totransmit signals representing uplink control data and user data to theeNodeB. The eNodeB 210 includes a transmitter 211, a receiver 212 and acontroller 213, where the controller 213 is configured to control thetransmitter 211 to transmit signals representing control data and userdata to UEs within a coverage area such as the UE 101, thus providing awireless access interface to UEs within the coverage area. Thecontroller 213 is also configured to control the receiver 213 to detectsignals representing user control and uplink data and estimate the dataconveyed by these signals.

The electromagnetic spectrum and in particular the radio frequencyportion over which wireless systems such as that illustrated in FIG. 1operate is a scarce resource and therefore its use is commonlycontrolled by an official government organisation. As a result of this,if a communications network operator wishes to have exclusive use of aparticular portion of the spectrum or a range of frequencies they arerequired to obtain a license to the portion by paying for its use. Sucha process of licensing is commonly performed via an auction or via adirect decision of the official organisation in control of spectrumallocation. For example, in the UK portions of the frequency spectrumaround 900 MHz, 1800 MHz and 2.1 GHz are allocated to mobiletelecommunications for second, third and fourth generation networkswhere each frequency portion may be further divided into separateallocations for different network operators each of which pays for theuse of their allocation. Although the use of licensed spectrum reducesthe likelihood of experiencing interference because the operator mayhave exclusive use of it and thus may lead to improved systemperformance, by virtue of the cost of licensed spectrum and the limitedquantity of it, capacity limitations may arise from the use of licensedspectrum alone. Systems that operate in accordance with the LTEstandard(s) have conventionally operated in licensed portions of thespectrum but the desire for additional capacity has led to the use ofunlicensed radio frequency spectrum for LTE systems being proposed.Systems which are capable of LTE operation over unlicensed radiofrequencies may be referred to as LTE-U systems and the unlicensedspectrum may be used to provide stand alone LTE carriers or carrierswhich act as additional carriers for carrier aggregation for example

Communications System Operation in Unlicensed Spectrum

Unlicensed portions of the frequency spectrum consist of frequenciesover which no one has exclusive use but instead any device may use,possibly subject to power emission limitations and or methods ofbehaviour. For instance, the 2.4 GHz to 2.5 GHz range is specified as anindustrial, scientific and medical (ISM) band where devices such asmicrowaves and communications systems such as WiFi operate (IEEE 802.11telecommunications standard). A second ISM band also exists at 5.725 GHzto 5.875 GHz in which WiFi may also operate. In order to ensure that theISM bands remain usable for wireless communications certain behaviouralrules may be implemented. For example, if a high level of interferenceis experienced at a particular frequency by a device attempting totransmit, the device is required to reduce its transmission power ortransfer to another frequency rather than increase the transmissionpower as may occur in a licensed band. Such operation is commonlyreferred as the politeness principle and reduces the likelihood thattransmission powers of devices increase via a positive feedback loopuntil little or no communications can be achieved over the associatedfrequencies.

Due to the unknown nature of the users of the unlicensed bands such asthe 2.4 GHz and 5.8 GHz ISM bands, if LTE systems are to use thesefrequencies a method of determining the signals or interference presenton the frequencies of interest within the ISM band are required.Furthermore, it is likely that a condition of LTE-U operation is that itdoes not interfere with other communications systems utilising the ISMbands such as WiFi for example. Consequently, the operation of LTE-U isdependent on both establishing a hole(s) in the unlicensed spectrum inwhich a wireless access interface can be provided but also ensuring thatany LTE-U transmissions do not cause significant interference toco-existing systems utilising the unlicensed frequency band. Theoperation of LTE-U is currently in the early stages of development andhas therefore yet to be determined, consequently there are a number ofdifferent possible modes of operation. For example, an eNodeB mayprovide an LTE based wireless access interface concurrently on bothlicensed and unlicensed spectrum where control signalling is restrictedto transmission over the resources of the licensed bandwidth such thatthe wireless access interface of the unlicensed band simply acts toprovide additional data capacity. In this case downlink controlinformation specific to resource allocation in the unlicensedfrequencies may be transmitted over the licensed frequencies.Alternatively, the wireless access interfaces of the licensed andunlicensed band may be run as independent systems where both control anduser data are communicated over both the licensed and unlicensedfrequencies. Lastly, LTE-U may operate without a correspondingconventional LTE network running on licensed bandwidth so that an LTEwireless access interface is fully provided over an unlicensed frequencyband. However, regardless of the exact operation of the LTE and LTE-Usystems there is a common requirement that free resources in theunlicensed spectrum be identified for LTE-U to operate.

FIG. 3 provides a schematic diagram of an LTE system that includes aneNodeB 301 which provides an LTE wireless access interface to the UEssuch as UE 302 that are within the coverage area 303. Also in FIG. 3 aWiFi router is present which provides a wireless access interface inaccordance with any of the IEEE 802.11 standards to devices within thecoverage area 305. Conventionally the LTE wireless access interface willbe provided over licensed spectrum or frequency range and the WiFiwireless access interface will be provided over unlicensed spectrum orfrequency range such as the 2.4 GHz and 5.8 GHz bands. In suchconventional circumstances the two systems will coexist with little orno interference with one another due to their separation in frequency.However, if the eNodeB wishes to perform LTE-U operation over theunlicensed frequency band a number of problems regarding the WiFi systemmay occur. Firstly, if the eNodeB wishes to provide a wireless accessinterface in an unlicensed band without causing interference to the WiFisystem or experiencing interference from the WiFi system, it isnecessary that the eNodeB has knowledge of spectrum/frequency range(s)that the WiFi system is utilising. With such knowledge the eNodeB maythen identify candidate frequencies and times for the provision of afurther or third wireless access interface and thus position the thirdwireless access interface around the WiFi signals in both time and orfrequency. When the eNodeB is within the coverage area of a WiFi networkthe eNodeB may detect signals from the WiFi system directly andtherefore provide an LTE wireless access interface around the detectedWiFi signals. However, as is shown in FIG. 3 the coverage area of a WiFisystem is likely to be smaller than that provided by an eNodeB,consequently, it can not be guaranteed that an eNodeB can detect WiFisignals that will be within range of served UEs. Consequently, eNodeBtransmissions performed without knowledge the WiFi system's spectrumtransmissions may interfere with and receive interference from the WiFisystem. In FIG. 3, interference resulting from signals transmitted bythe WiFi and LTE systems are represented by dashed lines wheretransmissions 306 and 307 represents interference from the LTE systemtowards the WiFi system and transmission 308 represent interference fromthe WiFi system to the LTE system and in particular the interferencecaused by WiFi signals at the UE.

In addition to the scenario depicted in FIG. 3, an LTE system may alsowish to provide a third wireless access interface via the use of a femtoeNodeB. For example a femto eNodeB with a reduced coverage area comparedto eNodeB 303 may be positioned in the vicinity of UE 302. In such anexample, user plane data may be communicated via the femto eNodeB acrossan unlicensed band and control plane data still may be transmitteddirect to a macro eNodeB across the licensed band. In order for theimplementation of such an arrangement, the macro eNodeB will once againrequire knowledge of the use of the unlicensed spectrum by the WiFisystem in both time and frequency such that the likelihood ofinterference can be reduced. Once this information is known the eNodeBmay configure the femto eNodeB to provide the third wireless accessinterface around the WiFI signals.

FIG. 4a provides a schematic diagram of an example portion of theelectromagnetic radio frequency spectrum where there is a frequencybandwidth 401 licensed to an LTE system (first bandwidth), an ISMunlicensed frequency band 402, a frequency band 403 licensed to a thirdparty and a second ISM unlicensed frequency band 404. A conventional LTEsystem may operates in 401 but in an LTE-U system an eNodeB may also tryto establish an LTE wireless access interface in one or more of 402 and404 (second bandwidth).

FIG. 4b provides corresponding diagram of the example portion ofspectrum of FIG. 4a but additionally shows signals 411 to 413 which arepresent in the ISM bands and may be signals providing a WiFi wirelessaccess interface for example. If an eNodeB is to establish an LTE-Uwireless access interface in the ISM bands it is desirable that theLTE-U signals do not overlap with the signals 411 to 413 in thefrequency domain.

FIG. 4c provides corresponding diagram of the example portion ofspectrum of FIG. 4b where LTE signals 414 and 415 providing an LTEwireless access interface have been positioned in the unlicensedfrequency spectrum between the signals 411 to 413. Consequently, LTE-Ucan operate without receiving interference from or causing interferenceto the system from which the signals 411 to 413 originate.

In order to achieve the resource utilisation depicted in FIG. 4c it isrequired that the eNodeB is provided within an indication of signals inthe unlicensed spectrum in the vicinity of a UE. Although up to thispoint and in the remainder of the disclosure, WiFi is given as anexample of the interference other communications systems such asultra-wideband (UWB) and ISM devices may also be the interferer and theinterferee. However, due to the potential competing nature of WiFi andLTE-U it is important that these two systems do not adversely affect theoperation of each other and therefore shall be used as an exampleco-spectrum user for the remainder of the disclosure.

Spectrum Sensing

In accordance with the present disclosure a UE with which an eNodeBwishes to communicate via unlicensed spectrum is operable to provide anindication of WiFi signals which it can detect such that the eNodeB isprovided with time and frequency information on WiFi signals that it maynot be able to detect directly. This process may be referred to asremote signal detection or remote carrier sensing. Referring back toFIG. 3, eNodeB 301 or a femto eNodeB may wish to provide a wirelessaccess interface and a corresponding connection with UE 302 over the 5.8GHz ISM bandwidth over which the WiFi router 304 is also operating.Consequently, the eNodeB requires an indication of the frequencies andpossibly their use in time over which the WiFi router is providing itswireless access interface. Consequently it is necessary that a candidateUE provides the information because the eNodeB may be out of range of arelevant WiFi transmitter.

FIG. 5 provide a diagram of the messages that may be exchanged betweenan eNodeB and a UE when the eNodeB wishes to establish an LTE wirelessaccess interface in an unlicensed frequency band when there in anexisting connection between the UE and eNodeB. In FIG. 5 the left-handcolumn represents communications between the eNodeB and the UE over theunlicensed spectrum i.e. the LTE-U or third wireless access interface,and the right column represents communications between the eNodeB andthe UE over the licensed spectrum via the conventional LTE wirelessaccess interface. Firstly, presuming that the eNodeB already has aconnection with the UE via a licensed portion of the spectrum, theeNodeB may send a spectrum sensing request message 501 to the UE, wherethe message may provide one or more of an indication of the candidatefrequencies over which the eNodeB wishes to establish an LTE-U wirelessaccess interface and the type of system whose signals the UE shoulddetect for example. In some examples an indication of the candidatefrequencies and the type of system may predetermined and known at the UEand therefore not require specification in the sensing request message.In response to receiving the spectrum sensing request message, the UEbegins the process of detecting WiFi signals and other signals on thecandidate frequencies, a process which is referred to as spectrumsensing 502 in FIG. 5. Once the detection process has been completed theUE may then provide an indication of the signals and or the propertiesof the signals that it has detected in the candidate frequencies to theeNodeB in a reporting message 503, thus completing the remote spectrumsensing or remote signal detection process. As well as frequency domaininformation, the reporting message may also provide information on thepower of any signals that have been detected and any time domaininformation available. Based on the reporting message the eNodeB maythen establish a LTE-U wireless access interface in the free portions ofthe unlicensed spectrum via the transmission of control messages 504 and505. The establishment of the LTE-U wireless access interface may beperformed via both the conventional LTE wireless access interface andthe LTE-U wireless access interface depending on the control structureimplemented for the LTE-U wireless access interface. For example, insome examples user plane data may be transmitted across the wirelessaccess interface provided across the unlicensed frequency band with mostor all control data being transmitted across the licensed frequencyband. Once the LTE-U wireless access interface has been established,user data 506 may then be communicated across it. Although in FIG. 5spectrum sensing and the establishment of a third wireless accessinterface has been described with reference to a single eNodeB, a thirdwireless access interface may also be provided in association in a macroeNodeB and femto eNodeB. For example, the spectrum sending and wirelessaccess interface set may be performed using the sensing request message501, the reporting message 503 and the LTE-U setup message 504 via themacro eNodeB without transmissions over the unlicensed band i.e. message505. Once the wireless access interface is setup, the data transmissionmay then be performed over the unlicensed frequency band via a femtoeNodeB as opposed to a macro eNodeB.

The spectrum sensing operation may be performed in accordance with oneor more of a plurality of techniques, each of which may have a differentsensitivity to WiFi signals or other signals, where complex techniquesmay provide more detailed information on spectrum usage and thereforeallow more efficient use of the available unlicensed spectrum. Thetechnique to be used may be determined by the capabilities of thesensing UE or ‘sensitivity level’, or in some examples may be specifiedin the sensing request message and thus be determined by the eNodeBrequesting the spectrum sensing. In circumstances where the detectiontechnique is determined in accordance with the capabilities of thesensing UE, the UE may provide an indication of its level of sensitivityto the eNodeB via a transmission on the licensed band. Such anindication may in some examples be provided when a UE first enters thecoverage area of an eNodeB, in response to sensing request or inresponse to an explicit sensitivity level request from the servingeNodeB.

A most basic approach to spectrum sensing is to detect power spectraldensity or the energy present on each of the candidate frequencies. Thisapproach may be achieved by simple energy detection on the candidatefrequencies by the receiver of the UE. In some examples as well as theenergy level detected, the UE may also report any time variation in theenergy levels. The time domain information may for example be used toposition the signals providing an LTE-U wireless access interface bothin the frequency and time domains, possible via a time and frequencyhopping technique. The detection of energy on candidate frequenciesenables the UE to detect signals from both communications systems suchas WiFi but also interference from other sources such as microwaves forexample. However, although sensing interference in this manner has a lowcomplexity it does not provide information on the nature of theinterference or any information on the potential future behaviour of theinterference which may be used by the eNodeB to pre-emptively avoidinterface.

As an alternative or as well as detecting the energy of signals in thecandidate frequencies, further information may be obtained from thedetected signals by analysing data that may be represented by thesignals. For example, by detecting the various properties of a WiFipacket further information about WiFi signals may be obtained.

FIG. 6 provide a schematic diagram of an example IEEE 802.11 WiFi packet600 where the packet is formed from a preamble 601, a signalling portionof physical (PHY) header 602 and a data portion 603. Each of theseportions of the packet 600 provides different information on theproperties of the WiFi signals. For example the preamble provides anindication that it is a WiFi packet, the PHY header provides informationon the coding of the data within the packet and the duration of thepacket and the data itself may provide information on future packets aswell as the user data of the current packet.

In a second spectrum sensing approach the UE is configured to detect thepreamble of WiFi packets so that as well as establishing the frequencyand time domain behaviour of the signals the type of signals e.g. WiFimay be established. WiFi packets have a common preamble structure andtherefore a simple matched filter may be used to detect WiFi signals onthe candidate frequencies. As well as providing an indication that theinterference is WiFi, by detecting WiFi packet preambles, theprobability of detecting a WiFi signals may be increased compared toenergy detection alone. However, although an improvement in terms ofdetection compared to energy detection, preamble detection still doesnot provide an indication of the likely behaviour of the interferenceoutside of the spectrum sensing period and thus may still be view as areactionary technique as opposed to a proactive detection technique.

A third approach to spectrum sensing is to detect and decode thesignalling or PHY header portion of WiFi packets. Although this willrequire actual detection and estimation of the data conveyed by the PHYheader, such information includes the length of the packet, modulationscheme and coding rate thus allowing the eNodeB to schedule LTE-Utransmission around the WiFi packets in a proactive manner and thereforeincrease the efficiency with which available spectrum is used. Thisapproach to interference/WiFi detection represents an improvement overthe second approach in terms of performance as it provides informationon the behaviour of the signal outside of the sensing period butrequires additional resources in order to decode the header. Althoughadditional resources are required at the UE, by virtue of the fact thatthe PHY header is modulated with binary phase shift keying (BPSK) forall releases of the IEEE 802.11 standard, the UE will be able to decodeall PHY regardless of the IEEE 802.11 release the WiFi packets wastransmitted in accordance with.

A fourth approach to spectrum sensing of WiFi signals incorporatesvirtual carrier sensing where the UE processes entire detected WiFipackets including the data portion such that it can establish allproperties associated with the packets. In such an approach the UE willbe required to have WiFi baseband capabilities and be fully WiFioperable so that all data can be detected and estimation. For example,the UE may have to be operable to decode WiFi signals transmitted inaccordance with any of the IEEE 802.11 releases modulated using any ofthe available modulation schemes such as BPSK, quadrature phase shiftkeying (QPSK), 16 quadrature amplitude modulation and 64 QAM forexample. However, in exchange for this increasingly complex spectrumsensing, by virtue of being operable to fully decode WiFi packets the UEmay also be able to decode beacon and control packets which provideinformation on system configurations and request to send (RTS) and clearto send (CTS) message, respectively. Beacon packets sent by a WiFirouter may contain synchronisation information and capabilityinformation on the WiFi router, thus providing the UE and eNodeB withfurther information on the behaviour of the WiFi wireless accessinterface and signals in both frequency and time. RTS and CTS messagesare exchanged in WiFi systems for virtual carrier sensing and mayprovide an indication of the length of future packets and therefore theperiod of time that a data exchange will take to conclude. Once the UEhas reported an indication of this information back to the eNodeB theeNodeB may then schedule transmission accordingly to the temporalinformation included in the RTS and CTS messages. The additionalinformation provided by the detection and estimation of beacon and RTSand CTS packets may in turn assist with optimising the positioning of aLTE wireless access interface in an unlicensed band and increase theefficiency with which resources of the unlicensed band are used withrespect to the preceding three spectrum sensing techniques

FIG. 7 provides a schematic diagram of a WiFi message exchange where RTSand CTS messages are utilised to establish the occupancy of thefrequency channels across which the WiFi wireless access interface isprovided. A transmitting entity firstly sends a RTS message 701 to theintended recipient, where the RTS message indicates the length of theintended transmission. When sufficient resources of the wireless accessinterface are available the intended recipient will then transmit a CTSmessage 702 to the transmitter indicating among other things how longthe wireless access interface will be available for. Once received atthe transmitter, the transmitter will transmit the data 703 and thereceiver will acknowledge the successful reception of the data via anacknowledgement 704. By this process of virtual carrier sensing, thirdparties may avoid collisions with transmissions from other transmittingnodes which it can not directly detect because they are out of range.This situation is commonly referred to as the hidden node scenario andis depicted in FIG. 8.

In FIG. 8 the transmitting node 801 has a coverage area of 802, thereceiving node 803 has a coverage area of 804 and the third party node805 has a coverage area of 806. As a result of these coverage areas thetransmitting node and the third part node area are unaware of eachother's existence and therefore in scenarios where virtual carriersensing is not in operation, they may transmit concurrently to thereceiving node and therefore interfere with each other. However, byrequiring a CTS message prior to transmission the third party will holdits transmission thus avoiding a potential collision betweentransmissions. An LTE UE such as the third party in FIG. 8 may in somecircumstances be considered to be the hidden node and therefore only beable to receive transmissions from the receiving node. Consequently, byvirtue of decoding the entirety of WiFi packets and performing virtualcarrier sensing, once an indication of the CTS packets has been receivedat the eNodeB, the LTE-U wireless access interface can be position awireless access interface around transmissions from the transmittingnode so that interference is not experienced at the receiving node eventhough the transmitting node is out of range of both the eNodeB and theUE.

The above described remote signal detection or remote carrier sensingmay be performed prior to the establishment of a LTE-U wireless accessinterface in an unlicensed frequency band but it may also be performedperiodically in order that an up to date frequency map of user of theunlicensed frequency band is maintained at the eNodeB. The variousremote carrier sensing techniques described above represent aprogressive trade-off between performance and complexity and thereforeeach technique may be selected based on the resource at the UE, theexpected interference in the unlicensed frequency band or the resourceof the unlicensed frequency band required to provide the LTE-U wirelessaccess interface. For example, a non-WiFi capable UE may only conductenergy detection where as a fully functional smart phone required a highdata-rate connection may perform full WiFi packet detection andestimation so that the LTE-U wireless access interface can be optimisedaround the present and future time and frequency properties of the WiFisignals.

Various further aspects and features of the present invention aredefined in the appended claims and various combinations of the featuresof the dependent claims may be made with those of the independent claimsother than the specific combinations recited for the claim dependency.Modifications may also be made to the embodiments hereinbefore describedwithout departing from the scope of the present invention. For instance,although a feature may appear to be described in connection withparticular embodiments, one skilled in the art would recognise thatvarious features of the described embodiments may be combined inaccordance with the disclosure.

The following numbered clauses provide further aspects and examples ofthe present disclosure:

-   -   1. A communications device comprising a transmitter, a receiver        and a controller operable to transmit and to receive signals        representing data to and from a network element across a first        wireless access interface operating according to a first        wireless telecommunications standard, the first wireless access        interface being provided by the network element and access to        resources of the first wireless access interface being        controlled by the network element, wherein the controller is        configured        -   to control the receiver to perform detection of signals            transmitted across a second wireless access interface            operating according to a second wireless telecommunications            standard which is different to the first wireless            telecommunications standard, and        -   to control the transmitter to transmit a reporting message            to the network element across the first wireless access            interface, the reporting message including an indication of            one or more properties of signals that have been detected            across the second wireless access interface.    -   2. A communications device according to clause 1, wherein the        signals transmitted across the first wireless access interface        are transmitted across a first frequency range and the signals        transmitted across the second wireless access interface are        transmitted across a second frequency range, the first and        second frequency ranges being substantially mutually exclusive.    -   3. A communications device according to clause 2, wherein the        controller is configured        -   to control the receiver to receive a sensing request message            from the network element, the sensing request message            providing an indication of the second frequency range, and        -   to control the receiver to perform the detection of signals            transmitted across the second wireless access interface            using the second frequency range in response to receiving            the sensing request message.    -   4. A communications device according to clauses 2 or 3, wherein        the receiver is operable to perform the detection of signals        transmitted across the second wireless access interface in        accordance with one or more of a plurality of detection        techniques, each of the plurality of detection techniques having        a different level of sensitivity to the signals transmitted        across the second wireless access interface.    -   5. A communications device according to clause 4, wherein one of        the detection techniques includes detection of the energy        present in the second frequency range.    -   6. A communications device according to clause 4, wherein the        signals transmitted across the second wireless access interface        represent one or more packets, each packet including a preamble        portion, a header portion and a data portion, and one of the        detection techniques includes detection of the preamble portion.    -   7. A communications device according to clause 4, wherein the        signals transmitted across the second wireless access interface        represent one or more packets, each packet including a preamble        portion, a header portion and a data portion, and one of the        detection techniques includes detection of the preamble portion        and detection and estimation of the data of the header portion.    -   8. A communications device according to clause 4, wherein the        signals transmitted across the second wireless access interface        represent one or more packets comprising data, each packet        including a preamble portion, a header portion and a data        portion, and one of the detection techniques includes detection        of the preamble portion, detection and estimation of data of the        header portion, and detection and estimation of data of the data        portion.    -   9. A communications device according to any of clauses 4 to 8,        wherein the controller is configured to control the transmitter        to transmit to the network element an indication of one of more        of the plurality of detection techniques the receiver can        perform.    -   10. A communications device according to clause 8, wherein the        data portion includes collision avoidance information, and the        controller is configured to perform virtual carrier sensing of        the second wireless access interface based upon the collision        avoidance information and provide an indication of the virtual        carrier sensing in the reporting message.    -   11. A communications device according to any of clauses 2 to 10,        wherein the second frequency range includes frequencies from an        unlicensed portion of the radio frequency electromagnetic        spectrum    -   12. A communications device according to any preceding clause,        wherein the second wireless access interface operates according        with one or more of the IEEE 802.11 standards.    -   13. A communications device according to any preceding clause,        wherein the first wireless access interface operates according        to a 3GPP LTE standard.    -   14. A communications device according to any preceding clause,        wherein the properties of the detected signals include one or        more of temporal properties and power spectral density        properties.    -   15. A network element comprising a transmitter, a receiver and a        controller operable to provide a first wireless access interface        operating according to a first wireless telecommunications        standard to a communications device and transmit and receive        signals representing data to and from the communications device        across the first wireless access interface, access to the first        wireless access interface being controlled by the network        element, wherein the controller is configured        -   to control the transmitter to transmit a sensing request            message to the communications device, the sensing request            message providing an indication of a second wireless access            interface that operates according to a second wireless            telecommunications standard which is different to the first            wireless telecommunications standard and a request for the            communications device to detect signals transmitted across            the second wireless access interface, and        -   to control the receiver to receive a reporting message from            the communications device, the reporting message providing            an indication of one or more properties of signals detected            by the communications device across the second wireless            access interface.    -   16. A network element according to clause 15, wherein the        signals transmitted across the first wireless access interface        are transmitted across a first frequency range and the signals        transmitted across the second wireless access interface are        transmitted across a second frequency range, the first and        second frequency ranges being substantially mutually exclusive.    -   17. A network element according to clause 16, wherein control        the sensing request message includes an indication of the second        frequency range.    -   18. A network element according to clause 16, wherein the        detection of signals transmitted across the second wireless        access interface is performed in accordance with one of a        plurality of detection techniques, each of the plurality of        detection techniques having a different level of sensitivity to        the signals transmitted across the second wireless access        interface.    -   19. A network element according to clause 18, wherein the        controller is configured to control the receiver to receive from        the communications device an indication of one of more of the        plurality of detection techniques the communications device is        operable to perform.    -   20. A network element according to any of clauses 16 to 19,        wherein the controller is configured to control the transmitter        and the receiver to provide a third wireless access interface in        response to receiving the reporting message, the third wireless        access interface being provided in portions of the second        frequency range indicated by the reporting message as having a        substantial absence of signals transmitted across the second        wireless access interface.    -   21. A network element according to any of clauses 16 to 20,        wherein the second frequency range includes frequencies from an        unlicensed portion of the radio frequency electromagnetic        spectrum.    -   22. A network element according to any of clauses 15 to 21,        wherein the second wireless access interface operates according        to one or more of the IEEE 802.11 standards.    -   23. A network element according to any of clauses 15 to 22,        wherein the first wireless access interface operates according        to a 3GPP LTE standard.    -   24. A wireless communications system comprising a network        element and a communications device, the network element        comprising a transmitter, a receiver and a controller operable        to provide a first wireless access interface operating according        to a first wireless telecommunications standard to the        communications device, control access to the first wireless        access interface and to transmit and to receive signals        representing data to and from the communications device, the        communications device comprising a transmitter, a receiver and a        controller operable to transmit and receive signals representing        data to and from the network element, wherein the controller of        the network element is configured        -   to control the transmitter of the network element to            transmit a sensing request message to the communications            device, the sensing request message providing an indication            of a second wireless access interface that operates            according to a second wireless telecommunications standard            which is different to the first wireless telecommunications            standard and a request for the communications device to            detect signals transmitted across the second wireless access            interface, and        -   to control the receiver to receive a reporting message from            the communications device, the reporting message providing            an indication of one or more properties of signals detected            by the communications device across the second wireless            access interface, and the controller of the communications            device is configured        -   to control the receiver of the communications device to            receive the sensing request message and in response to            perform detection of signals transmitted across a second            wireless access interface, and        -   to control the transmitter of the communications device to            transmit the reporting message to the network element.    -   25. A method for remote signal detection at a communications        device, the communications device being operable to transmit and        to receive signals representing data to and from a network        element across a first wireless access interface operating        according to a first wireless telecommunications standard, the        first wireless access interface being provided by the network        element and access to resources of the first wireless access        interface being controlled by the network element, wherein the        method includes        -   performing detection of signals transmitted across a second            wireless access interface at the communications device, the            second wireless access interface operating according to a            second wireless telecommunications standard which is            different to the first wireless telecommunications standard            and        -   transmitting a reporting message to the network element from            the communications device across the first wireless access            interface, the reporting message including an indication of            one or more properties of signals that have been detected            across the second wireless access interface.    -   26. A method for remote signal detection from a network element,        the network element being operable to provide a first wireless        access interface operating according to a first wireless        telecommunications standard to a communications device and        transmit and receive signals representing data to and from the        communications device across the first wireless access        interface, access to the first wireless access interface being        controlled by the network element, wherein the method includes        -   transmitting a sensing request message to the communications            device from the network element, the sensing request message            providing an indication of a second wireless access            interface operating according to a second wireless            telecommunications standard which is different to the first            wireless telecommunications standard and a request for the            communications device to detect signals transmitted across            the second wireless access interface, and        -   receiving at the network element a reporting message from            the communications device, the reporting message providing            an indication of one or more properties of signals detected            by the communications device across the second wireless            access interface.    -   27. A method for remote signal detection in a wireless        communications system, the system comprising a network element        operable to provide a first wireless access interface operating        according to a first wireless telecommunications standard to a        communications device, control access to the first wireless        access interface and to transmit and to receive signals        representing data to and from the communications device, the        communications device being operable to transmit and receive        signals representing data to and from the network element, the        method including        -   transmitting a sensing request message to the communications            device from the network element, the sensing request message            providing an indication of a second wireless access            interface operating according to a second wireless            telecommunications standard which is different to the first            wireless telecommunications standard and a request for the            communications device to detect signals transmitted across            the second wireless access interface,        -   performing detection of signals transmitted across a second            wireless access interface at the communications device in            response to receiving the sensing request message, and        -   transmitting a reporting message from the communications            device to the network element, the reporting message            providing an indication of one or more properties of signals            detected by the communications device across the second            wireless access interface.    -   28. A communications device as substantially hereinbefore        described with reference to the accompanying drawings.    -   29. A network element as substantially hereinbefore described        with reference to the accompanying drawings.    -   30. A communications system as substantially hereinbefore        described with reference to the accompanying drawings.

The invention claimed is:
 1. A communications device comprising atransmitter, a receiver and a controller operable to transmit and toreceive signals representing data to and from a network element across afirst wireless access interface operating according to a first wirelesstelecommunications standard, the first wireless access interface beingprovided by the network element and access to resources of the firstwireless access interface being controlled by the network element,wherein the controller is configured to: control the receiver to performdetection of signals transmitted across a second wireless accessinterface operating according to a second wireless telecommunicationsstandard which is different to the first wireless telecommunicationsstandard; and control the transmitter to transmit a reporting message tothe network element across the first wireless access interface, thereporting message including an indication of one or more properties ofsignals that have been detected across the second wireless accessinterface, wherein the signals transmitted across the first wirelessaccess interface are transmitted across a first frequency range and thesignals transmitted across the second wireless access interface aretransmitted across a second frequency range, the first and secondfrequency ranges being substantially mutually exclusive, and thecontroller is configured to control the transmitter and the receiver tocommunicate via a third wireless access interface that is provided bythe network element in response to the reporting message, the thirdwireless access interface being provided in portions of the secondfrequency range indicated by the reporting message as having asubstantial absence of signals transmitted across the second wirelessaccess interface.
 2. The communications device as claimed in claim 1,wherein the controller is configured to: control the receiver to receivea sensing request message from the network element, the sensing requestmessage providing an indication of the second frequency range; andcontrol the receiver to perform the detection of signals transmittedacross the second wireless access interface using the second frequencyrange in response to receiving the sensing request message.
 3. Thecommunications device as claimed in claim 1, wherein the receiver isoperable to perform the detection of signals transmitted across thesecond wireless access interface in accordance with one or more of aplurality of detection techniques, each of the plurality of detectiontechniques having a different level of sensitivity to the signalstransmitted across the second wireless access interface.
 4. Thecommunications device as claimed in claim 3, wherein one of thedetection techniques includes detection of the energy present in thesecond frequency range.
 5. The communications device as claimed in claim3, wherein the signals transmitted across the second wireless accessinterface represent one or more packets, each packet including apreamble portion, a header portion and a data portion, and one of thedetection techniques includes detection of the preamble portion.
 6. Thecommunications device as claimed in claim 3, wherein the signalstransmitted across the second wireless access interface represent one ormore packets, each packet including a preamble portion, a header portionand a data portion, and one of the detection techniques includesdetection of the preamble portion and detection and estimation of thedata of the header portion.
 7. The communications device as claimed inclaim 3, wherein the signals transmitted across the second wirelessaccess interface represent one or more packets comprising data, eachpacket including a preamble portion, a header portion and a dataportion, and one of the detection techniques includes detection of thepreamble portion, detection and estimation of data of the headerportion, and detection and estimation of data of the data portion. 8.The communications device as claimed in claim 3, wherein the controlleris configured to control the transmitter to transmit to the networkelement an indication of one of more of the plurality of detectiontechniques the receiver can perform.
 9. The communications device asclaimed in claim 7, wherein the data portion includes collisionavoidance information, and the controller is configured to performvirtual carrier sensing of the second wireless access interface basedupon the collision avoidance information and provide an indication ofthe virtual carrier sensing in the reporting message.
 10. Thecommunications device as claimed in claim 1, wherein the secondfrequency range includes frequencies from an unlicensed portion of theradio frequency electromagnetic spectrum.
 11. The communications deviceas claimed in claim 1, wherein the properties of the detected signalsinclude one or more of temporal properties and power spectral densityproperties.
 12. A network element comprising a transmitter, a receiverand a controller operable to provide a first wireless access interfaceoperating according to a first wireless telecommunications standard to acommunications device and transmit and receive signals representing datato and from the communications device across the first wireless accessinterface, access to the first wireless access interface beingcontrolled by the network element, wherein the controller is configuredto: control the transmitter to transmit a sensing request message to thecommunications device, the sensing request message providing anindication of a second wireless access interface that operates accordingto a second wireless telecommunications standard which is different tothe first wireless telecommunications standard and a request for thecommunications device to detect signals transmitted across the secondwireless access interface; and control the receiver to receive areporting message from the communications device, the reporting messageproviding an indication of one or more properties of signals detected bythe communications device across the second wireless access interface,wherein the signals transmitted across the first wireless accessinterface are transmitted across a first frequency range and the signalstransmitted across the second wireless access interface are transmittedacross a second frequency range, the first and second frequency rangesbeing substantially mutually exclusive, and the controller is configuredto control the transmitter and the receiver to provide a third wirelessaccess interface in response to receiving the reporting message, thethird wireless access interface being provided in portions of the secondfrequency range indicated by the reporting message as having asubstantial absence of signals transmitted across the second wirelessaccess interface.
 13. The network element as claimed in claim 12,wherein the sensing request message includes an indication of the secondfrequency range.
 14. The network element as claimed in claim 12, whereinthe detection of signals transmitted across the second wireless accessinterface is performed in accordance with one of a plurality ofdetection techniques, each of the plurality of detection techniqueshaving a different level of sensitivity to the signals transmittedacross the second wireless access interface.
 15. The network element asclaimed in claim 14, wherein the controller is configured to control thereceiver to receive from the communications device an indication of oneof more of the plurality of detection techniques the communicationsdevice can perform.
 16. The network element as claimed in claim 1,wherein the second frequency range includes frequencies from anunlicensed portion of the radio frequency electromagnetic spectrum. 17.A method performed by a communications device comprising a transmitter,a receiver and a controller configured to transmit and to receivesignals representing data to and from a network element across a firstwireless access interface operating according to a first wirelesstelecommunications standard, the first wireless access interface beingprovided by the network element and access to resources of the firstwireless access interface being controlled by the network element,wherein the method comprises: controlling the receiver to performdetection of signals transmitted across a second wireless accessinterface operating according to a second wireless telecommunicationsstandard which is different to the first wireless telecommunicationsstandard; controlling the transmitter to transmit a reporting message tothe network element across the first wireless access interface, thereporting message including an indication of one or more properties ofsignals that have been detected across the second wireless accessinterface, wherein the signals transmitted across the first wirelessaccess interface are transmitted across a first frequency range and thesignals transmitted across the second wireless access interface aretransmitted across a second frequency range, the first and secondfrequency ranges being substantially mutually exclusive; and controllingthe transmitter and the receiver to communicate via a third wirelessaccess interface that is provided by the network element in response tothe reporting message, the third wireless access interface beingprovided in portions of the second frequency range indicated by thereporting message as having a substantial absence of signals transmittedacross the second wireless access interface.